ThreadRestrictions: disallow blocking IO on the UI thread

chrome/browser/visitedlink_master.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/visitedlink_master.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <io.h>
 #include <shlobj.h>
 #endif  // defined(OS_WIN)
 #include <stdio.h>
 
 #include <algorithm>
 
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/rand_util.h"
 #include "base/stack_container.h"
 #include "base/string_util.h"
+#include "base/thread_restrictions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/history/history.h"
 #include "chrome/browser/profile.h"
 
 using file_util::ScopedFILE;
 using file_util::OpenFile;
 using file_util::TruncateFile;
 
 const int32 VisitedLinkMaster::kFileHeaderSignatureOffset = 0;
@@ skipping 210 matching lines @@
   history_service_override_ = NULL;
   suppress_rebuild_ = false;
   profile_ = profile;
 
 #ifndef NDEBUG
   posted_asynchronous_operation_ = false;
 #endif
 }
 
 bool VisitedLinkMaster::Init() {
+  // We probably shouldn't be loading this from the UI thread,
+  // but it does need to happen early on in startup.
+  //   http://code.google.com/p/chromium/issues/detail?id=24163
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   if (!InitFromFile())
     return InitFromScratch(suppress_rebuild_);
   return true;
 }
 
 VisitedLinkMaster::Hash VisitedLinkMaster::TryToAddURL(const GURL& url) {
   // Extra check that we are not off the record. This should not happen.
   if (profile_ && profile_->IsOffTheRecord()) {
     NOTREACHED();
     return null_hash_;
@@ skipping 618 matching lines @@
         AddFingerprint(*i, false);
       added_since_rebuild_.clear();
 
       // Now handle deletions.
       DeleteFingerprintsFromCurrentTable(deleted_since_rebuild_);
       deleted_since_rebuild_.clear();
 
       // Send an update notification to all child processes.
       listener_->NewTable(shared_memory_);
 
+      // We shouldn't be writing the table from the main thread!
+      //   http://code.google.com/p/chromium/issues/detail?id=24163
+      base::ThreadRestrictions::ScopedAllowIO allow_io;
       WriteFullTable();
     }
   }
   table_builder_ = NULL;  // Will release our reference to the builder.
 
   // Notify the unit test that the rebuild is complete (will be NULL in prod.)
   if (rebuild_complete_task_.get()) {
     rebuild_complete_task_->Run();
     rebuild_complete_task_.reset(NULL);
   }
@@ skipping 90 matching lines @@
 }
 
 void VisitedLinkMaster::TableBuilder::OnCompleteMainThread() {
   if (master_)
     master_->OnTableRebuildComplete(success_, fingerprints_);
 
   // WILL (generally) DELETE THIS! This balances the AddRef in
   // VisitedLinkMaster::RebuildTableFromHistory.
   Release();
 }